1. Field of the Invention
The present invention generally relates to storage devices, and more particularly to a storage drive that operates on a network.
2. Related Art
FIG. 1 illustrates a conventional storage area network (SAN) 100. A tape library 102 includes multiple tape drives 104, into which are inserted tape cartridges 106 for storing data. A user on the network, by using a controlling node such as an automation server 108, may wish to transfer files between the library and other nodes on the network, such as video servers 110.
Current tape drives and libraries communicate data using a device protocol, such as SCSI or fiber channel interface. However, users on the network may be operating workstations that communicate with the network according to a network protocol, such as the Ethernet Internet protocol. Referring to FIG. 1, an archive (or storage) manager 112 performs the protocol translation between the device protocol and the network protocol in a conventional network. Based upon that translation, data movers 114 in the archive manager 112 respectively read or write data from and to the tape drives 104 according to the device protocol.
Moreover, typical tape drives employ a raw data format requiring the addressing of information in block format, for example. However, users typically want to access data using a file format. The archive manager 112 handles the conversion between the file format and the raw data format. The archive manager, using a database server 116, also stores metadata about the data stored in the libraries, providing a mapping of files to physical locations of the data in the libraries.
Conventional tape backup host applications store on tape a set of selected files from hard drive for back up. The application may store a table of contents (TOC) for each backup data set. The TOC may be stored on tape, as well as in semiconductor memory on the server running the host application. Multiple backup data sets may store some files in common, e.g., the same file stored at different times.
The application uses the TOC to determine where the drive head must move to access a specified file in a particular data set on the tape. However, the host application must have specific knowledge of all data sets on the tape to find the TOC containing the block location for the specified file. Because multiple copies of the same file may be stored in different data sets, the host must employ a complicated set of rules to find the correct TOC containing the correct block locations for the correct copy of the specified file. The disadvantage of this arrangement is that it relies solely on the host application to find the requested data file. Also, the host must read all the TOCs, until the correct TOC is located, to find the correct block locations for the correct copy of the specified file.
Another disadvantage to the current SAN configuration is that the software available on the market today for the archive manager and data movers is proprietary and may change over time. This contrasts with the need to be able to archive data in libraries for very long durations without concern for dependency on third party software.